ICMs are used as electrolyte membranes in a variety of electrochemical applications, such as electrochemical devices (e.g., fuel cells), chloroalkali applications, and vapor permeation/separation applications. With respect to fuel cells, ICMs may function as electrolyte membranes capable of transferring protons (e.g., proton-exchange membranes). ICMs are particularly suitable in fuel cell applications because they may replace hazardous acidic liquid electrolytes, such as those used in phosphoric acid fuel cells.
A fuel cell such as a proton-exchange membrane fuel cell typically contains a membrane electrode assembly (MEA), which is a catalyst coated membrane disposed between a pair of gas diffusion layers. The catalyst coated membrane itself typically includes an electrolyte membrane disposed between a pair of catalyst layers, where an ICM may function as the electrolyte membrane. The respective sides of the electrolyte membrane are referred to as an anode portion and a cathode portion. In a typical proton-exchange membrane fuel cell, hydrogen fuel is introduced into the anode portion, where the hydrogen reacts and separates into protons and electrons. The electrolyte membrane transports the protons to the cathode portion, while allowing a current of electrons to flow through an external circuit to the cathode portion to provide power. Oxygen is introduced into the cathode portion and reacts with the protons and electrons to form water and heat.
ICMs used in the above-discussed applications typically require adequate mechanical strengths (e.g., tear resistance). Previous attempts to enhance the mechanical strengths of ICMs involved increasing the thicknesses of the membranes. However, increases in membrane thicknesses generally decrease the ion conductivities of such membranes. Moreover, membranes that are inherently weak at small thicknesses (e.g., less than about 50 micrometers) require reinforcement with additional materials, which also undesirably cause the resulting membrane to have increased thicknesses and reduced ion conductivity.